Railway signaling



t 1,646 401 9ct 25 1927 R. M. GlLsoN v RAILWAY SIGNALING Filed July 1v. 1926 LS'S UIB 3.0.0.1 m UA 2. h -f y INVENTOR:

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,QW/QQ z' e( Patented 'Oct 25,` 1927.

UNITED sTATEgS SWITCH sa SIGNAL COMPANY, or

PENNSYLVANIA.

Appiiation filed Juiy 17,

My invention relatesto railway signaling,

4 and particularly to signalingof the type of current to the track rails.

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanyinng drawing, Fig. 1 is a diagrammatic v iew showing one` form of apparatus embodying my invention. Fig. Q is a diagrammatic view showing a modification of the apparatus shown in Fig.r 1 and also embodying my invention. i

. Similar reference characters' refer to similar parts in each ofthe views.

.Referring first to Fig. 1, the reference characters 1 and laidesignate the track rails of ya railway track along which traffic normally vmoves in the direction indicated by the arrow. These rails are divided by insulated joints 2 to form a track section A-B, and .this track section is provided with a track circuit comprising asource of current located Lat the exit end of the sectionand a track relay D connected across the rails at .the entrance end of the section.` As here shown, the source of track circuit current is a transformer T, the secondary` 3 of which is connected across the rails of section A-f-B through an impedance 5, and the primary .4 of which is supplied with alternating current from the secondary 6 fof, aline transformer UB. ,The primary 7 of transformerUB is constantly. supplied with alternating current fromy a suitable source, not shown in the drawing, and the same thing is trueof the primary 7 of line 4transformer UA, hereinafter. referred to. p

' The section A-B is provided with coding means C forpperiodically interrupt-ingtheA supplyv of current from the transformer UB to the transformer T. As here shown, this coding means comprises aV relay having a back contact 8 interposedpbetween the transformer will operate continuously.,y

PATE l g ROBERT M. .GILSON, OF PITTSBRGIL-PENNSYLVANA, ASSIGNOR T0 TH 'UNION RAILWAY srGNALING.

192s. seriaINQ. izzwee;A

iUB and the transformer T. Relay isipro-i vided with a` circuit which passes from the secondary 6 of the transformer UA, through 'back contact 9 of track relay D, winding lof. relay C, andvback contact 17 of relay C to secondary Gof transformer UA. It` willbe seen, therefore, that when track relay ,D is cle-energized, that is, when section Az-,B is

SW'ISSVVALE, PENNSYLVANIA, A CORPORATION OIE occupied by a t'rainrelay willjbefintermittently energized,` and so will periodically yinterrupt the supply of current to the track rails fromA transformer TIB. The coding relay C will usually be controlled in` part by invention. Furthermore, back vcontact V9 of trafli'c conditions in advance ofsection l vbut this control forms no part of my present track relay D may be omitted from the cirf cuit for relay C, so that'the codingfrelay v The 'reference` character y relay which is supplied with energyfromthe tracklrailsofsection AfB. As hereshown, the primaryv .11i of a transformer G .is vconnectedacross the rails, and the secondary 15 of this transformer' is connected: with the relay. Ethrough they medium ofthe rectifier F comprising fourqasymmetric units k10, 11, .12 and 13.v These units are connected in such manner as to constitute 'a fullfwave 1E designaties "i" rectifier, whereby unidirectional,current is supplied to the relay E eachV time thatal'tenv nating current isapplied to the track circuit,

that is, each time that back contact 8 of coding relay Gis closed. .It will be observed that f the asymmetric units 11 andlO constitute a shunt path for relay E, which v path oifersa low resistance tocu'rrent induced therein by* the decayof flux in the relay core lwhen'the relay becomes de-energi7-ed, and it will also be observedthat the asymmetric 4,units 13 and 12 constitute a similar shuntpath. Itfollows thatV during each interruption-of'track circuit current these shunt paths retard the decay of flux in the relay core and so retard f the opening ofthe relay armature. This retardation is suiiicient to preventthe relay armature from openingduring the periodic interruptions of. track circuit current while the coding relay C isin operation. Y

When a train enters lsection A-QB, itfdeenergizesthe track relay D and so sets the c'odingcrelay C into operatiom` Whenthe train reaches agpoint close to the vtrans.-

fOrmerG, it reduces thecurrent supplied to 1 relay E to such a value that this relay opens, and the relay thereafter remains open until the train leaves section AMB. rlrack relay y ample, as a highway crossing signal S,

located adjacent point B. This signal Sis controlled by'a back contact 16 of relay E, through a circuit which is obvious from the drawing, j, and so it follows that the signal S"willbe setinto operation when a train approaches transformer G` and will cease operation after the train passes point B.` Y

`With the apparatus shown in ,Fig. 1, I

have found that as a train approaches `the transformer G, the voltage applied to relay ,E is gradually reduced until'a value maybe remain energized until another train approaches transformer G.` y

One i'eature of my invention is that it is uniiecessary to make vthe relay E slow` releasing in character, and another feature `is that it is unnecessary4 to `interpose a secy ond relay between relayfE andthe t-rack i appended fel-aimsA `without reached at' which the relay does not receive enough energy to remain closedduring` the interruptions of the track circuit current, with the result that'tor a short distance of train `movement the relay E may intermit` tently closerand open its contact 16, To avoidA this possible intermittent operation of relay E, the relay may be supplied with energy `in themanner illustrated in Fig. 2.

` Referring to this view, theiasymmetric units 11 and 12V are interposed between transformer G and the windingot relay E in the same manner as in Fig. V1,but the connections between transiformer G and` relay E which `include theA other two asymmetric units 10 and 13 also include `frontcontacts 18 and 19, respectively, of the relay E.` `It follows that when therelay E is energized, full wave uni-.directional current is supplied to the winding. of thisA relay, whereas when the relay is cle-energized, one halt ofeach `wave. Y*is suppliedto the winding through asymmetric units 11 and12`, but the other half of each wave is `prevented from flowing in the winding of the relay. elVifththe structure shown `in Fig.` 2, ywhen a"train approaches transformer G, it will reachf a pointat which relay E will open during an interruption of the track circuit current, andthereafter the relaywill receive only one lhalf of `eac-h alternatingcurrent wave. Since the voltage required to pick up `the relay E on one-half of an alternating current wave is about four ,times the voltage reqiiiredtopick" itup, when supplied with full wave uni-directional current, it will bev clear that once the relay is opened'in response to a train approaching transformer G, itl will not close again until the train has passed point B and normal voltage is again applied to `the transformer G.V `F ull wave uni-directional current will then again be vappliedto relay"E, `,so that this relay will Y rails.

Although I have herein shown and de-v scribed vonly two forms of apparatus embodying my invention,` it is understood that various changes'pand niodiications may/be made therein within the scope of rthe `departing from" the spirit and scope of my invention. l

Havingthus described my invention what Iclaim is: y

1. In combination, a section of railway track provided' with a source of current, coding means for periodically interrupting the supply of current'trom saidsource to the rails ot said section, r a relay receiving energy from said rails, rectifying means interposed between saidv rails and saidrelay `and constituting,aA shunt path aroundthe relay whichprevents the relay from releasing its `armature during the interruptionsfof currentwhile said coding'means is in operation, and signaling means controlled by said relay( j Y f A "2. ln combination, afwsection. of railway track provided with a source of alternating current, codingmeans for periodically interrupting the supplyfof current from said sourceV to the rails ofthe section`,`a relay, rectifying means interposed4 betweengthe track rails and said relay for supplying the relay with unidirectional,current from the track rails while alternating current is being supplied to the rails. through `said coding Vmeans', said Vrectii'ying means constituting a shunt around the relay to prevent the frelay from releasing' its armature duringthe in# terruptions currentV by said coding means, andsignaling means controlledby said relay.

3. In combination, a section of railway track providedfwith a sourceof alternating current, coding means torperiodically interrupting the supply of current from` said source .to the rails oi the section, a relay, rectifying. fnieans interposed between the `,track.rails andsaid relay forsupplying the relay with "uni-directional current ,while alernating current is `being supplied to the railsl through said coding means, said rectify- Iing,meansconstitutinga shunt around`V` the relay topreventfthe relay lfrom releasing its armature during the interruptionsof current byasaid coding means, meanscontrolled by the armature of said 'relay y for Yremoving a portion of said lrectiiymg means from the circu`1t..forA the relay when the relay armature Y signaling means ,controlled ajln combination, a section of railway track provided with a source of alternating current, coding means for periodically interrupting the supply of current from said source tothe rails of the section, a relay, two asymmetric units interposed between the track rails and the two terminals respectively of the winding of said relayfor permitting one halt of each alternating current wave but not the other half to flowv through said winding, two other asymmetric units interposed between the track rails and the two terminals respectively of said winding for the second half of each wave but not the first to low through said winding, and signaling means controlled by said relay.'

5. In combination, a section of railway track provided with a source lof alternating current, coding means for periodically interrupting the supply of current from said source to the rails of the section, a relay, two asymmetric units interposed between the track rails and the two terminals respectively of the winding of said rela-yy for permitting one half of each alternating' current wave but not the other half to flow through said winding, two other asymmetric units interposed between the track rails and the two terminals'respectively of said winding for` permitting the Second halt of each wave but not the first half to flow through said winding, the connections between the relay winding and the track rails through the second pair ofasymmetric units including front contacts of said relay whereby the supply ofthe second half of each wave to the relay winding is discontinued when the relay armatu-re is open, and slgnahng means f controlled by said relay.

6. In combination, a section ,of railway track provided with a source of alternating current, coding means for periodically interrupting the supplya of current from said source to the rails of the section, a transformer the primary oi' which is vconnected with the rails of said section, a relay receiving energy from the secondary ofsaid transformer, and rectifying means interposed between the secondary ot' said transformer and said relayV for supplying the relay with unidirectional current while alternating current is being supplied to the rails through said t ROBERT M. eiLsON. 

